The present invention relates to a serial shed weaving machine with a weaving rotor. The weaving rotor includes combs having shed retaining elements for the warp threads. The combs form open warp sheds which travel in the warp direction. The weaving rotor also has guide channels comprised of a plurality of channel elements for guiding the weft the threads which are transported by a flowing fluid. Each of the channel elements has an exit gap or slot in a wall to permit exit of the weft thread and is mounted so as to be movable with respect to the other channel elements. The weft exit slot is adapted to be closed in response to movement of the channel elements. Each channel element has its forward and rearward ends (with respect to the weft insertion direction) configured such that when the channel elements of a given guide channel are positioned for weft insertion, the channel elements form a continuous closed guide channel.
Such a serial shed weaving machine is described in German Offenlegungsschrift No. 31 11 780 (corresponding to U.S. patent application Ser. No. 06/241,934). In this known weaving machine, each guide channel is comprised of two combs comprised of dents which may be moved into and out of the midst of the warp threads with the dents forming the channel elements. The dents are relatively thin, and their end faces (i.e., their forward and rearward faces in the weft insertion direction) have complementary wedge surfaces which facilitate the movement of the combs into and out of one another. The dents of each comb are attached to at least one bar which extends over the width of the weaving machine. The bars are operatively connected to drive levers which are controlled via cams mounted on the machine frame to cause movement of the combs into and out of one another.
This known serial shed weaving machine is intended to enable weft insertion by aspirated air, i.e., suction air pressure, rather than blown air. The use of suction air provides not only substantial energy savings but also much more even (non-turbulent) passage of the weft thread and better overall control of the weft insertion. It has been found, however, that due to the thinness of the dents there are a large number of potential leakage locations which interfere with the aim of satisfactory weft insertion by aspirated air. In addition, the drive system for the combs including bars, drive levers, and cams employs a large number of mechanically manipulated and loaded parts which are necessarily subject to undesirable wear.
It is an object of the present invention to improve and refine the known serial shed weaving machine in such a way that the weft threads can be inserted by aspirated air. A further object of the present invention is to provide a serial shed weaving machine in which the system comprising the guide channels and the operating and control arrangement for the channel elements is as simple as possible both structurally and from a manufacturing and systems reliability standpoint. In particular, the system is comprised of a small number of parts which are subjected to minimal mechanical load and stress.
These objects and others are achieved according to the present invention by channel elements having an elongated tubular shape. The length of the channel elements is a multiple of the thickness of one of the shed retaining elements. The elements are movable back and forth in the weft insertion direction by a drive such that when the channel elements are moved in one direction the closed guide channel is opened. At this time, gaps develop between the elements, and each channel element is moved out of the corresponding part of the warp shed. When the channel elements are moved in the other direction, each channel element is moved into the corresponding part of the warp shed and the guide channel is again closed. The total excursion of each channel element in one direction is at least equal to its length in the weft insertion direction.
The inventive use of elongated, tubular, channel-like dents for forming the guide channel instead of the formerly employed narrow, plate-like dents drastically reduces the number of potential leaks, by more than an order of magnitude, such that the weft threads may now be inserted with aspirated air, which provides the advantages mentioned. The fact that the movement of the channel elements is in the weft insertion direction makes it possible to drive and control the elements by simpler arrangements than in the prior art where movement of the dents was rotational in a plane transverse to the insertion direction.